Which? executive director Richard Lloyd said: "The government, regulator and energy companies have failed to move quickly enough to improve things for consumers when so many are struggling to pay their bills.

"That is why we decided to launch The Big Switch. This is a completely new way to buy energy as a group. The bigger the group, the stronger our bargaining power will be."

The Big Switch will take place as a reverse auction, with energy companies invited to submit their lowest price per kilowatt of electricity and cubic metre of gas.

Which? said that once a deal has been secured, those who have signed up will be notified by email or text message and can then choose whether or not to accept it – they will not be obliged to switch.

According to Which?, UK consumers are collectively paying £4.1bn a year more than they need to by not switching their energy tariff to the cheapest deal.

The Big Switch campaign will roll-out across the UK with a series of regional events in Reading, Glasgow, Manchester, Birmingham and Cardiff throughout February and March.

David Babbs, executive director of 38 Degrees, said: "We are all sick of gas and electricity companies ripping us off. If thousands of customers band together we will have the bargaining power to do something about it.

"The big energy companies act like they are untouchable, but this people-powered campaign can turn the tables and bring down prices for everyone."

The energy and climate change secretary Edward Davey said he was "delighted" with the scheme: "I have long believed collective purchasing will be a game-changer in terms of handing power back to consumers."

He added: "I want to make it easier for consumers to club together and use collective purchasing power to reduce their gas and electricity bills. We are looking hard at how we can do this and how we can remove barriers to enable more initiatives like The Big Switch.

"At the same time we are working with Ofgem to simplify energy tariffs, make energy bills easier to understand, and boost competition in the market so that consumers can get the best deals."